This invention relates to a door of a microwave oven of the type in which a door cover, made of a heat-resistant material, is provided around a peripheral portion thereof.
Ordinarily, a microwave oven comprises a cabinet, a heating and cooking chamber provided with an access opening, a door for closing and opening the access opening, and a high frequency oscillator for radiating a high frequency electromagnetic wave in to the heating chamber. A control panel having control switches and the like is provided in a front part of the cabinet adjacent to the door.
The door of the microwave oven comprises a door plate of a frame-like configuration having a central window, upper and lower sashes secured to the upper and lower edges of the door plate, a perforated screen provided to cover the central window of the door plate, outer and inner barriers made of a transparent material provided on the front side and the rear side of the screen, respectively, a contact plate formed integrally with the screen to be brought into contact with the cabinet, and a door cover which is provided to cover a gap formed between the contact plate and the peripheral edges of the door. Because of high heat-insulating requirement, the door cover is ordinarily made of a synthetic resin mixed with glass fibers and is ordinarily secured to the door plate by means of machine screws and the like. The use of machine screws and the like, however, entails disadvantages of increasing the number of parts required, increasing time and labor required for the assembling, and hence increasing the production cost.
SUMMARY OF THE INVENTION
An object of this invention is to provide a door of a microwave oven wherein the above described difficulties of the conventional construction can be substantially eliminated.
Another object of this invention is to provide a door of a microwave oven wherein the door cover is provided with engaging portions and held in its position by simply engaging the engaging portions with a related member.
These and other objects of the present invention can be achieved by providing a door for a microwave oven, disposed forward of an access opening formed in a cabinet of the oven, for opening and closing the access opening. The door comprises a door plate of a frame-like construction having a central window, upper and lower sashes secured to the door plate so as to cover upper and lower ends of the door plate, an outer barrier provided forwardly of the door plate to cover the central window, a screen having a number of perforations provided to cover the central window on the rear side thereof, a contact plate formed integrally with the screen to surround the same so that the contact plate is contactable with the cabinet at a portion surrounding the access opening, an inner barrier provided in contact with a rear side of the screen, a door cover engageable with the upper and lower sashes and the contact plate and having an opening at the center. The upper and lower sashes have rearward edges bent inwardly to hold the door cover. The contact plate has outer peripheral portions first bent forwardly and then bent outwardly thereby forming stepped portions for supporting the door cover. The door further comprises at least a pair of engaging portions provided along an internal edge of the door cover to be brought into engagement with mating portions of the contact plate.